Single-ended halogen-cycle incandescent lamp with bridgeless mount assembly

ABSTRACT

The coiled filament of a tubular halogen-cycle type lamp is suspended within the envelope by a mount assembly which is so constructed that the lead wires are rigidly coupled to and electrically insulated from each other without the quartz bridge member customarily employed. Discoloration of the envelope in the region of the bridge member is inhibited and the lumen maintenance of the lamp is thus enhanced.

United States Patent [1 1 Martin et al.

111 3,760,217 1451 Sept. 18, 1973 SINGLE-ENDED HALOGEN-CYCLEINCANDESCENT LAMP WITH BRIDGELESS MOUNT ASSEMBLY [75] Inventors: JackMartin, Paramus; Joseph S.

Gorecki, West Caldwell, both of NJ.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

221 Filed: Aug. 25, 1972 21 App]. No.: 283,682

[52] US. Cl 313/276, 313/222, 313/279, 313/286 [51] Int. Cl. H0lk 1/14,HOlk 1/18 [58] Field of Search 313/222, 271-276, 313/279, 285, 286, 289

[56] References Cited UNITED STATES PATENTS 1,842,167 1/1932 Hall313/273 8/1947 Cartun ..3l3/279 8/1932 Cartun ..3l3/274 PrimaryExaminer-Rudolph V. Rolinec Assistant Examiner-Marvin NussbaumAttorney-A. T. Stratton et a1.

[57] ABSTRACT The coiled filament of a tubular halogen-cycle type lampis suspended within the envelope by a mount assembly which is soconstructed that the lead wires are rigidly coupled to and electricallyinsulated from each other without the quartz bridge member customarilyemployed. Discoloration of the envelope in the region of the bridgemember is inhibited and the lumen maintenance of the lamp is thusenhanced.

10 Claims, 6 Drawing Figures PATENTEDSEPB'QHI 3,760,217

SHEH 2 BF 2 FIGS.

SINGLE-ENDED HALOGEN-CYCLE INCANDESCENT LAMP WITH BRIDGELESS MOUNTASSEMBLY CROSS-REFERENCE TO RELATED APPLICATION BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to electricincandesent lamps I and has particular reference to an improved filamentmount structure for a quartz-halogen lamp.

2. Description of the Prior Art Halogen type incandescent lamps are wellknown in the art and are used in various industries and applicationswhere a compact source of light or heat is required. A persistentproblem in the manufacture of these lamps is that of connecting the endsof the lead wires to the coiled filament and maintaining the latter incentralized position within the tubular quartz envelope during the lifeof the lamp.

According to the teachings of the aforesaid copending application, themount structure is simplified by bending the end of the long lead wireinto a loop which nests within the top of the bulb and thus serves as anintegral mount-positioning-and-bracing means. In one embodiment, aquartz bridge member joins the lead wires at the basal end of the lampto rigidify the mount and serve as an anchorage point for afilament-support wire. In the other embodiment disclosed in theaforesaid copending application, the lower bridge member is omitted andthe straight axially-extending portion of the long lead wire is encasedin an insulating sleeve of quartz or the like to prevent it fromcontacting and short-circuiting the filament.

A quartz-halogen lamp having a bridge member that joins the long andsort lead wires together at the presssealed end of the lamp and has afused hollow tip at the top of the bulb which is engaged by the innerend of the long lead wire is disclosed in U.S. Pat. No. 3,497,753 issuedFeb. 24, 1970 to L. S. Huston, Jr. A tubular incandescent lamp having along lead wire that is encased in a glass tube and held incentrally-disposed position within the envelope by bending the end ofthe long lead wire into a loop which nests within a tapered dome formedon the end of the envelope is disclosed in U.S. Pat. No. 3,300,675issued Jan. 24, 1967 to Z. Deshaw. An incandescent lamp having afilament that is suspended in coaxial position within a tubular envelopeby an auxiliary filament-support wire of spiral configuration isdisclosed in U.S. Pat. No. 923,797 issued June 1, 1909 to R. McNeil]. Aquartz-halogen lamp having a coiled-coil filament that is held incoaxial position within a tubular envelope by a pair of wire connectorshaving laterally-offset coil segments that are attached to the ends ofthe lead wires and respective legs of the filament is disclosed in U.S.Pat. No. 3,486,065 issued Dec. 23, 1969 to J. Martin.

While the aforementioned prior art mount structure held the filament inthe desired axial position within the envelope and provided satisfactoryelectrical connections between the leads and filament, it has been foundthat the presence of the relatively massive bridge member of quartz orthe like at the bottom of the bulb causes the latter to darken andbecome dicolored as the lamp burns. It is theorized that the bridgemember acts as a sort of heat sink" which reduces theoperatingtemperature of the bulb wall in this region to a low enough value topermit vaporized tungsten from the filament to condense and remain onthis part of the bulb. Another possibility is that the bridge memberacts as a baffle which obstructs and impedes the circulation of thehalogen gas through the bottom of the bulb and thus prevents it fromgettering deposited tungsten particles and returning them back to thefilament. Whatever the reason, the portion of the envelope adjacent thebridge tends to blacken during lamp life thus reducing the lumenmaintenance and lamp efficiency.

It would accordingly be desirable to provide a rugged mount structurefor a tubular halogen lamp which does not require a vitreous bridgemember to rigidify the lead wires, or a filament support that requiressuch a bridge member to hold it in place. It would be especiallydesirable to provide a bridgeless mount structure for high-wattagehalogen lamps of long length which thus have filament that requires somemeans of intermediate support.

SUMMARY OF THE INVENTION The foregoing objectives are achieved inaccordance with the present invention by placing an insulating sleeve ofquartz or the like over a medial portion of the long lead wire that isoffset toward and extends along the inner wall of the envelope and byjoining the end of the long lead to one end of the filament coil bycoupling means which engages the hollow tip of the bulb so that the longlead and coupling means serves as a brace and centralizing structure forthe filament. The end of the short lead wire is connected to thefilament and attached to an insulated part of the long lead by a secondcoupling means thereby further strengthening the mount and providing avery rugged lamp.

In lamps having long singly-coiled filaments, intermediate support ofthe filament is achieved by means of wire loops that are attacheddirectly to the filament and extend laterally toward and are seatedagainst the insulated section of the long lead and surrounding portionsof the bulb wall. Various forms of coupling means for joining the leadwires to each other and to the respective ends of the filament aredisclosed.

The present invention thus provides a rugged and durable mount assemblywhich eliminates the need for bridge members and thus prevents prematurebulb blackening.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of theinvention will be obtained from the exemplary embodiments shown in theaccompaying drawings, wherein:

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is shown an 800watt single-ended incandescent lamp of the halogen-cycle type whichembodies one form of the invention and comprises the usual tubularenvelope 12 of quartz (orother suitable high melting point material)that is terminated by a hollow fused tip 13 and is hermetically closedat its opposite end by a press seal 14 and contains an elongatedsingly-coiled filament 15 of tungsten wire. The envelope 12 in thisparticular embodiment is of the T 2 A type (5/16 inch or 7.9 millimetersOD) and contains an inert gas such as a mixture of argon and nitrogenthat is dosed with a suitable halogen such as iodine or bromine. Thefilament 15 is suspended in coaxial position within the envelope 12 by amount assembly which includes a short lead 16 and a long lead 17 thatare embedded and anchored in the press seal 14 and connected by theusual ribbon conductors and outer leadsto the terminals of a base 18that is cemented to the press seal.

As will be noted in FIG. 1 and shown .more particu-' larly in FIG. 2,the filament coil 15 is maintained in the desired coaxial locationwithin the envelope 12 by offsetting the central portion of the longlead 17 so that it is disposed adjacent and extends along the inner wallof the envelope, encasing this lead portion in a sleeve 22 of quartz (orother material such as alumina or a suitable ceramic), and bending thefree end of the long lead to provide a transversely-extending arm 19which is terminated by an axially-extending coiled segment 20 that isdimensioned to threadably fit into and engage the end of the filamentcoil 15. A short spud wire 21 is partly inserted into the coiled segment20 of the long lead 17 and securely fastened in such position by hotclamping thereby electrically and mechanically coupling the members andpermitting the end of the spud wire 21 to enter and engage the envelopetip 13.

The short lead wire 16 is electrically connected to the other end of thefilament 15 and mechanically attached to an insulated part of the longlead 17 by a connector 23 consisting of rigid wire that is wound intotwo laterally-offset coiled segments 24 and 25 that are joined by atransverse arm portion 26. The coiled segment 24 is of such size that itthreadably engages and is interlocked with the end of the helicalfilament 15 and snugly receives the end of the short lead 16 to which itis secured by welding. The length of the arm portion 26 is such that theother coiled segment 25 can be slipped over the insulating sleeve 22(when the mount is being assembled) and thus maintain that end of thefilament 15 in the desired coaxial alignment. The connector 23 effects asnug fit with the sleeve 22 and is locked in place thereon by fusing ashort collar 28 of quartz or the like to the sleeve 22 (after thefilament 15 is pulled taut) so that the end of the collar 28 is seatedagainst the coiled segment and acts as a stop. This arrangement permitsa wider tolerance for the inside diameter of the coiled segment 25 andautomatically positions the connector 23 on the long lead 17 duringmount assembly.

As will be noted in FIG. 2, the singly-coiled filament 15 is devoid ofany depending legs and consists of a coil barrel of cylindricalconfiguration. The filament 15 (as illustrated in FIG. 1) is supportedat a plurality of spaced points along its length by wire spirals 30 thatare attached directly to the turns of the filament l5 and extendlaterally toward and nestingly engage the insulating sleeve 22 and thecurved inner wall of the envelope 12.

In the alternative lamp embodiment 10a shown in FIG. 3, a'slightlymodified filament mount assembly is employed. Coupling of the componentsat the upper end of the mount according tothis embodiment is achieved byterminating the transverse arm segment 19a of the long lead 17a by acoiled segment 20a that extend axially toward the bulb tip 13a ratherthan toward the proximate end of the filament 15a. The coiled segment20a and spud wire 21a are fastened to each other and to the end of thefilament 15a by a coil insert 27 that threadably engages and isinterlocked with the end of the filament barrel and snugly receives andis hot clamped to the spud wire 21a. The other end of the coil insert 27is threaded into and interlocked with the coiled segment 20a of the leadwire so that the protruding end of the spud wire 21a enters and engagesthe tip 13a of the envelope 12a when the mount assembly is inserted intothe envelope prior to the press-sealing operation. Of course, as will berecognized by those skilled in the art, at this stage of lampmanufacture the fused tip 13a has not yet been formed and the end of thespud wire 21a is positioned within the depending exhause tubulationwhich is subsequently melted and severed to form the fuse tip 13a, afterthe envelope 12a has been evacuated and dosed with fill gas and halogen.

The lower end of the filament 15a is coupled to the short lead wire 16aby providing a pair of coiled segments 31 and 32 on the end of the shortlead, which segments are joined by an opened turn 33 (shown more clearlyin FIG. 4). The end of the filament 15a is threaded over and interlockedwith the coiled segment 32 and a modified connector 23a is employed tosecure the short lead 16a to an insulated part of the long lead 17a. Theconnector 23a is generally U-shaped and has a longitudinally-disposedcoiled segment 25a and a longitudinal-depending straight leg segment 34that are joined by a transverse arm segment 35 which is of such lengththat it permits the leg segment 34 to be inserted through the openedturn 33 and into coiled segment 31 of the short lead 16a. As before,coiled segment 25a is dimensioned to effect a snug fit with the tubularinsulator 220.

In FIG. 5 there is shown a 250 watt halogen-cycle lamp 10b that has acoiled-coil filament 15b which is much shorter and thus does not requireany auxiliary filament-support means. The envelope 12b is of the T-4type one-half inch or 12.7 millimeters OD) and is closed by a fusedhollow tip 13b at one end and by a press seal 14b at its opposite end inthe customary fashion. In accordance with this embodiment, the shortlead 16b is attached directly to an insulated part of the long lead 17bby bending the end of the short lead toward the long lead and formingthe end of the short lead into a longitudinal-extending coiled segment36 that encircles and grips the insulator sleeve 22b and is terminatedby a transverse arm segment 37 and a downwardly-extending leg segment38. The conjoined end of the filament 15b is formed with an open turn 39in the primary winding so that a short axially-extending coil section 40is provided at that end of the filament. The leg segment 38 is insertedthrough the open turn 39 and into the coiled section 40. The upper endof the filament 15b is coupeld to an axially-extending coiled segment20b on the long lead wire 17b by bending one end of the spud wire 21binto a partial turn which is threaded into the primary winding of thecoiled-coil filament to form a button hook connection, and then slippingthe coiled segment 20b over the straight portion of the spud wire 21band hot clamping them together.

Alternatively, the upper end of the coiled-coil filament 15b can also beprovided with an opened primary turn and a depending coil section andthe end of the long lead 17b can be bent into an L-shaped hook that isinserted into the opened turn and through the coiled section of thefilament to provide the same basic type of connection as that employedat the lower end of the filament.

In the alternative 250 watt lamp embodiment c shown in FIG. 6, amodified coupling arrangement is used to fasten the short lead wire 160to the coiled-coil filament c and the insulated portion of the long leadwire 17c. As shown, the end 41 of the short lead 160 is bent into apartial turn which is screwed into the end turn of the filament 15c andis welded to a coiled leg segment 42 of a connector 23c. The latter isU-shaped and has another longitudinally-extending coiled leg segment 43that is slipped over and snugly on the insulator sleeve 22c whichencloses the offset portion of the long lead wire 17c. The coiled legsegments of the connector 23c are joined by a transverse arm segment 44,as shown.

The other end of the filament 15c is coupled to the end of the long leadwire 17c in the same manner as in lamp embodiment 10b so that the end ofthe spud wire 21c engages the tip 13c of envelope 12c.

We claim as our invention:

1. A single-ended halogen-cycle incandescent lamp comprising:

a tubular envelope of vitreous light-transmitting material that containsa halogen additive and has a press seal at one end and a closedcentrallydisposed fused hollow tip at its opposite end,

a coiled tungsten filament of elongated configuration suspended inlongitudinal position within said en- I velope, and

a bridgeless mount assembly holding said filament in such suspendedposition comprising (a) a pair of rigid lead wires of unequal lengththat are embedded in said press seal and extend into said envelope, (b)means electrically insulating amedial portion of the long lead wire, (c)first coupling means fastening the end of the. long lead wire to one endof said filament and engaging the hollow tip of said envelope, and (d)second coupling means fastening the short lead wire to the other end ofsaid filament and to an insulated part of the long lead wire, said longlead wire being offset toward and extending along the wall of saidenvelope and being terminated by a transverse arm segment that extendstoward the filament and, in turn, is terminated by alongitudinally-disposed coiled segment that is in substantially coaxialalignment with the filament and constitutes part of said first couplingmeans. 2. The halogen incandescent lamp of claim 1 wherein said firstcoupling means includes a spud wire that extends into the tip of theenvelope and into the coiled end segment of the long lead wire andassociated end of the filament.

non-conductive material that encloses the offset medial portion of thelong lead wire which extends along the 5 wall of said envelope.

4. The halogen incandescent lamp of claim 3 wherein a wire loop isanchored to a medial part of said coiled filament and extendstransversely therefrom toward said insulating sleeve and the wall ofsaid envelope and thereby constitute auxiliary support means for saidfilament.

5. The halogen incandescent lamp of claim 3 wherein said second couplingmeans inlcudes a wire connector component that extends transversely fromthe associated end of said filament to the long lead wire and is.terminated by a coiled segment that encircles and grips said insulatingsleeve.

6. The halogen incandescent lamp of claim 5 wherein;

the coiled end segment of said long lead wire extends into and isthreadably interlocked with the associated end of the filament, a spudwire extends from the tip of said envelope into the coiled end segmentof said log lead wire, and

the end of said wire connector component that is fastened to the otherend of said filament comprises a coiled segment that extends into and isthreadably interlocked with the filament.

7. The halogen incandescent. lamp of claim 5 wherein; H

the coiled end segment of saidlong lead wire is axially spaced from theassociate-d end of the filament and is of substantially the same innerdiameter as the coiled filament,

a coiled connector component extends into and is threadably interlockedwith the adjacent portions of the coiled end segment of said long leadwire and associated end of the filament, and

a spud wire extends from the tip of said envelope into the said coiledconnector component. 8. The halogen incandescent lamp of claim 5wherien;

the end of the short lead wire is also terminated by alongitudinally-disposed coiled segment that (a) extends into and isthreadably interlocked with the associated end of said filament, and (b)is joined to a second coiled segment by an opened turn,

said wire connector component has a depending uncoiled leg segment thatextends through the opened turn and into the said second coiled segmentof the short lead wire that protrudes from the associated end of saidfilament.

9. The halogen incandescent lamp of claim 3 wherein;

said filament is of the coiiled-coil type, and

the short lead wire is (a) offset toward the long lead wire, (b) has amedial coiled segment that encircles and grips said insulating sleeve,and (c) is terminated by leg segment that is welded to a coiled sectionof the filament which is joined to the filament barrel by an openedprimary turn.

10. The halogen incandescent lamp of claim 3 wherein;

said filament is of the coiled-coil type, and

said second coupling means inlcudes a generally U- shaped wire connectorthat is terminated at each end by a longitudinally-disposed coiled legsegment, one of which encirclesand grips said insulating sleeve and theother of which encircles and is secured to the end of the short leadwire.

1. A single-ended halogen-cycle incandescent lamp comprising: a tubularenvelope of vitreous light-transmitting material that contains a halogenadditive and has a press seal at one end and a closed centrally-disposedfused hollow tip at its opposite end, a coiled tungsten filament ofelongated configuration suspended in longitudinal position within saidenvelope, and a bridgeless mount assembly holding said filament in suchsuspended position comprising (a) a pair of rigid lead wires of unequallength that are embedded in said press seal and extend into saidenvelope, (b) means electrically insulating a medial portion of the longlead wire, (c) first coupling means fastening the end of the long leadwire to one end of said filament and engaging the hollow tip of saidenvelope, and (d) second coupling means fastening the short lead wire tothe other end of said filament and to an insulated part of the long leadwire, said long lead wire being offset toward and extending along thewall of said envelope and being terminated by a transverse arm segmentthat extends toward the filament and, in turn, is terminated by alongitudinally-disposed coiled segment that is in substantially coaxialalignment with the filament and constitutes part of said first couplingmeans.
 2. The halogen incandescent lamp of claim 1 wherein said firstcoupling means includes a spud wire that extends into the tip of theenvelope and into the coiled end segment of the long lead wire andassociated end of the filament.
 3. The halogen incandescent lamp ofclaim 1 wherein said insulating means comprises a sleeve of electricallynon-conductive material that encloses the offset medial portion of thelong lead wire which extends along the wall of said envelope.
 4. Thehalogen incandescent lamp of claim 3 wherein a wire loop is anchored toa medial part of said coiled filament and extends transversely therefromtoward said insulating sleeve and the wall of said envelope and therebyconstitute auxiliary support means for said filament.
 5. The halogenincandescent lamp of claim 3 wherein said second coupling means inlcudesa wire connector component that extends transversely from the associatedend of said filament to the long lead wire and is terminated by a coiledsegment that encircles and grips said insulating sleeve.
 6. The halogenincandescent lamp of claim 5 wherein; the coiled end segment of saidlong lead wire extends into and is threadably interlocked with theassociated end of the filament, a spud wire extends from the tip of saidenvelope into the coiled end segment of said log lead wire, and the endof said wire connector component that is fastened to the other end ofsaid filament comprises a coiled segment that extends into and isthreadably interlocked with the filament.
 7. The halogen incandescentlamp of claim 5 wherein; the coiled end segment of said long lead wireis axially spaced from the associated end of the filament and is ofsubstantially the same inner diameter as the coiled filament, a coiledconnector component extends into and is threadably interlocked with theadjacent portions of the coiled end segment of said long lead wire andassociated end of the filament, and a spud wire extends from the tip ofsaiD envelope into the said coiled connector component.
 8. The halogenincandescent lamp of claim 5 wherien; the end of the short lead wire isalso terminated by a longitudinally-disposed coiled segment that (a)extends into and is threadably interlocked with the associated end ofsaid filament, and (b) is joined to a second coiled segment by an openedturn, said wire connector component has a depending uncoiled leg segmentthat extends through the opened turn and into the said second coiledsegment of the short lead wire that protrudes from the associated end ofsaid filament.
 9. The halogen incandescent lamp of claim 3 wherein; saidfilament is of the coiiled-coil type, and the short lead wire is (a)offset toward the long lead wire, (b) has a medial coiled segment thatencircles and grips said insulating sleeve, and (c) is terminated by legsegment that is welded to a coiled section of the filament which isjoined to the filament barrel by an opened primary turn.
 10. The halogenincandescent lamp of claim 3 wherein; said filament is of thecoiled-coil type, and said second coupling means inlcudes a generallyU-shaped wire connector that is terminated at each end by alongitudinally-disposed coiled leg segment, one of which encircles andgrips said insulating sleeve and the other of which encircles and issecured to the end of the short lead wire.